Conventional base load power production plants or facilities—for example nuclear power plants or fossil-fuel power plants—can deliver power as required to an electricity grid. A grid operator may determine the base load at any specific time, i.e. the amount of power required by customers supplied by the grid, and issue appropriate references to any power plant that feeds into the grid. Such power plants are generally characterized by a constant power output. In the case of power production plants that generate electricity using renewable energy sources such as wind energy or solar energy, the amount of power that can be output depends to some extent on the environmental situation, for example the strength of the wind in the case of a wind power plant; or the time of day and extent of cloud cover in the case of a photovoltaic power plant. In certain situations, such a conventional “renewable” power plant may have the potential to produce more power than is actually needed, but since the power plant may only generate as much power as is required to fulfil a grid demand, the additional power that it is capable of producing is effectively wasted since it cannot be fed into the grid. The amount of power generated by a power production facility is regulated or managed by a plant operator, which ensures that the power fed into the grid fulfils the grid requirements at all times. A power plant operator, for example a wind power plant “pilot”, is effectively separate and isolated from the grid operator. Therefore, in conventional arrangements, only the grid operator can make use of a power storage facility in which a power “surplus” could be stored for later use. However, the management of power storage facilities in isolation from the power generation plants means that these cannot be operated to optimally utilize their capabilities, and their management is also severely constrained by limitations imposed by grid requirements.